This invention relates to a windshield wiper adapted for use with the normally curved windshields of land, air and marine vehicles, in particular for trucks (lorries) and passenger automobiles.
Known windshield wipers of this kind have a predetermined sweeping angle of maximally about 180 degrees between two end positions, and comprise a wiper motor for reversing the direction of the sweeping wiper at each such end position and having a stub shaft, a wiper lever articulatedly connected with said stub shaft and adapted for being swung away from the said windshield, and a wiping arm carrying at least one wiping blade and being connected with the remainder of the wiper via a spring clip combination.
According to Lueger, "rororo" publication volume 13, page 523, the wiper lever carries out about 50 to 70 sweeping movements per minute, and the drive thereof comprises as a rule two velocity stages of 50 sweeps per minute and 70 sweeps per minute. In order to increase the effectiveness of the windshield wiper, it is used, generally, in combination with a windshield scourer, whose water can be heated by means of a heat exchanger whose construction is based on the principle of an immersion heater, and shield-cleaning agents can be added to the water.
Making use of these two auxiliary measures will provide an increase in scouring intensity, in particular as long as the wiping blade is still new, i.e. its edge has not yet been damaged.
These conditions change, however, very rapidly, when, for instance, wiping is done without the use of water or when the windshield wiper is employed in removing icing from the shield as it is often formed in winter.
A further problem, arising at least in certain types of vehicles having a curved windshield when trying to ensure a substantially uniform pressure of the wiper blade against the windshield, can be considered solved generally by the combination of the spring clip combination connecting the wiper lever and the wiper arm.
In spite of this relatively great technical effort, the known windshield wiper installations cannot overcome the dirtying effect occurring in particular when the roads are wet,--which effect is particularly strong when it is caused, for instance, by a preceding vehicle,--with sufficient quickness and with a satisfactory cleaning result; it thus becoming possible that traffic will be endangered by insufficient visibility.
This is true particularly when encountering oil- or silicone-containing layers of dirt which form streaks on the road encumbering the driver's view.
These streaks are, in fact, less disturbing in their effect when the windshield is dry; however, they are quickly regenerated when rain starts up again, and can often not be removed by a single sweep of the wiper blade even when repeated; often it becomes necessary to stop the vehicle and descend from it to clean the windshield by hand, e.g. with the aid of paper napkins.